Various fabrication processes including, without limitation, film deposition, film etching, and wafer or substrate inspection, and the like, are employed during the fabrication of integrated circuits. Such fabrication processes generally require that the semiconductor wafer or substrate be held in a fixed position within the fabrication apparatus.
The wafer or substrate is typically held in a fixed position using an electrostatic chuck (ESC) upon which the wafer or substrate is positioned and fixed by action of an electrostatic charge induced by the ESC. The ESC typically comprises a wafer support member formed of a dielectric material, an electrically conductive electrode and a high voltage power source (e.g., DC power supply) for charging the electrode to a high voltage (e.g., 500-700 volts). The electrostatic force that fixes the wafer or substrate to the ESC is generated by the potential difference created between the ESC with the high voltage applied thereto and the electric field applied by RF or microwave electric field generating means to a process gas in the apparatus to produce a plasma therein.
Removal of the wafer or substrate from the ESC (dechucking) may be accomplished by turning off high voltage power source and the electric field generating means. Because the wafer and the ESC are grounded, the electrostatic charge holding the wafer to the ESC drains to ground when the high voltage power source and the electric field generating means are turned off.
A problem with the this dechucking method is that a remnant of the electrostatic charge usually remains on the ESC after dechucking because the electrostatic charge can not drain instantaneously. The remnant electrostatic charge on the ESC attracts particles to the surface of the wafer or substrate. These particles often cause defects in subsequent processing.
Accordingly, an improved dechucking method and apparatus is needed which reduces particle contamination of the wafer or substrate.